Re: 35 hp Johnson carb tuning question

[vintin]

I’ve found with my 1957 35hp RDE that if the idle is set lean enough to not have some mid speed over richness…and a miss……that it suffers from cold lean sneezes. After the engine has warmed up the lean sneeze at idle goes away. With a cold start with me sitting at the motor giving it half choke after starting it eliminates the cold lean sneeze.

After getting your 35hp warmed up have somebody else drive and have them give it good throttle from a dead stop. If you get missing lean up the idle a little and try it again. Alternately, from a dead stop giving it good throttle if you get missing give the idle needle a good twist towards leaner side. You might be surprised and find that your missing or bogging is from the carb running a little fat in it’s mid range until the butterfly opens bringing the high speed jet into play. I did.

Then adjust the high speed needle following standard protocol.

Then fool with the low speed settings.

I’ve found that I can get a good non sneezing cold start if I fatten up the low speed jet about two numbers. Then of course it needs to be leaned out two numbers after warm up. This will wear out the packing washers fairly quickly.

It would be nice if these motors had a continually adjustable remote choke, but they don’t.

Do make sure as was mentioned earlier that the transition point where the high speed jet joins the low speed jet output is set correctly (carb synchronization). Ditto for the economizer adjustment. If you don’t know what these are, you’re going to have to know if you want your motor to run at it’s best.

Also see the thread on the use of a timing fixture on these motors.

When it all comes together these are beautifully running motors.

Is your motor passing good water flow?